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@uitrit tstrs @anni @fitta ALBERT S. GREENE, 4OIl WASHINGTON, DISTRICT OF COLUMBIA, ASSIQNOR TO JOHN F. OLMSTEAD, OF THE SAME PLACE. I

,Letters Patent No; 72,023, dated December4 10, 1867. I

y IMPROVEMENT IN STEAM-cauces.

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TO ALL WHOM IT MAY CONGERN: I

Be it known that I, ALBERT S. GREENE, of the city of Wasbingtop, and District of Columbia, have invented a new and useful Improvement in Steam-Gauges; and I do hereby declare that the following is a full, clear, andl exact description of the construction and operation of the same, reference being had to the accompanying drawings, making a part of this specification, iii whichi Figure 1 is a front view of my improved steam-gauge. Figure 2, a vertical section, as indicated by the line taken in the plane a: y of iig. 1. Like letters in both figures of the drawings indicate like` parts. p My improvement is intended to apply particularly to steam-gauges for measuring high pressures, but is equally applicable for low pressures, and for measuring pressures of any gases or liquids. l

It consists, first, of two separate and essential columns of mercury, communicating with each other at their p lower extremities by two flexible diaphragme of ditierent areas, the motion from the smaller one being transe iiiiii a, mitted to the larger by means of a solid double-headed lifter--the smaller diaphragm forming the top of a reservoir for the mercury in the primary column, the larger forming the bottom of a wide and shallow cistern for the mercury in the secondary column, the motion of mercury in which indicating the pressure on the p scale; second, providing the primary reservoir with a screw-plunger for diminishing or increasing its capacity, so that the mercury in the secondary column may be adjusted with nicety to the zero (0) point oi' the scale when varying therefrom, by reason of dili'erent temperatures of the surrounding atmosphere.

To enable any one skilled in the art to make and use my invention, I will proceed to dcscribe its construction and operation. Y

A is the primary column, which is to receive the pressure of steam to be measured through a pipe which will connect with its upper end. B is a casting, containing the primary reservoir I, which communicates with the primary column through a passage running horizontally, and thence vertically in the casting to the column, which is screwed into the casting. is the screwplunger h is a recess for packing, which will surround the plunger to prevent the mercury working out of the reservoir, and will be secured therein by the screw-nut l, Y with a metallic washer on the inside, 'fitting in the recess against the packing. c c are the smaller diaphragm, set in areeess of the casting over a small passage, m, communicating with the primary reservoir. The recess is provided with screw-threads on the inside, into which is screwed the smaller end of the box u, containing the lifter C, thasmaller head a of which rests on the smaller diaphragm c c. d d are the larger diaphragm, which rests on the larger head Z1 of the lifter. E E are a cap, which is screwed on to the larger end of the box n, forming the secondary reservoir. Fl is a glass tube for secondary column, which communicates with the reser-V voir, and is made tight to the cap by packing being placed around it in a recess, o, of the cap; the packing being secured by a screw-nut, 7c, with a metallic washer on the inside of it, fitting in the recess against the pack; ing. G is a brass case for protecting the glass tube; it is secured to the screw-nut k, and is made open on one side for the scale of the instrument. (See L'of fig. l.) fis a small piece of rubber, which, with the thumb'z screw g, closes the top lof the tube F, to secure the mercury during handling or` transportation of the instru;

ment.

The novelty of the primary column consists in its affording a protection for the iiexible diaphragm c e from thc heat of steam of high pressures, which, without this protection, would soon destroy the gum and prevent the proper action ofthe instrument, and also in balancing the weight of the lifter C, and the pressure of the mercury on its larger head, due to the height of mercury in the secondary column up to the zero (0) point ofthe scale, thereby making the gauge a perfect measure for low as well as high pressures.

The novelty of the screw-plunger consists in itsi'urnishing a delicate means of adjustment for the level of mercury in the secondary column to the zero (0) point' ofthe scale, as it may vary from expansion duc to differ-v ent temperatures of the medium surrounding the instrument, which adjustment does not act directly on the secondary' column, but by varying the head of mercury in the primary column, and thus the pressure on the diaphragm c c. i

'It will be seen that in the operation of the instrument, the mercury'in the primary column, from a pressure ofsteam, will press on the smaller diaphragm c c, and thus through the lifter C transmit motion to the largerl diaphragm d d, which, pressing on the mercury in the reservoir, tyill cause it to rise or fall in the secondary column inproportion to the degree of pressure which will be indicated on the scale ofthe instrument.

With my instrument I am enabled to measure pressures by the height of a column of mcrcurywithout particular reference to its diameter, (except that it must be small in comparison with' the area of the larger diaphragu1,) so that in case of the glass tube breaking, (the only part liable to break,) which constitutes the secondary mercury column for measuring the pressure; it may be readily replaced by another tube of nearly the same calibre, thus preserving the same scale and all other parts of the instrument perfect. The glass tube must be of small calibre compared with the areaof theplarger diaphragm, (as above statecL) for the purpose of keeping the motion of the diaphragms necessary for the proper action of the instrument within narrow limits.

In the use-of other steam-gauges for measuring high pressures, the height of tube or column of mercury necessary is found to be very inconvenient and sometimes diiicult in fixing them properly aboard of a ship or vessel, and besides being frequently injured in the transportation of them. My instrument can be made to occupy but little space, and at a considerably less cost, comparatively: speaking, and, consequently, will be found to be particularly a desirable and perfect measure for high pressures.

Having thus fully described my invention, what I claim therein as new, anddesire to secure by Letters Patent, is-

1. The construction of a steam-gauge, with two columns of mercury, A. and F, communicating with eacb other at their lowerextremities by means ofthe flexible diaphragmsc and d, and the solid double-headed lifter C, substantially'in the manner andfor the purpose-as herein set forth.

2. The solid double-headed lifter C, in combination with 'the flexible diaphragms c and d and the primary and secondary reservoirs, substantially in the manner and for the purpose as herein set forth.

3. The transmission of the pressure' of steam from one column to the other by means of a solid doubleheaded lifter, in combination with the flexible diaphragme e and d, substantially inthe manner and for the purv pose as herein set forth.

4. Providing the primary reservoir 4I with the screw-plunger H, substantiallv in the manner and for the purpose as herein set forth.

A. S. GREENE;

Witnesses l HALLET KILBOURN, W. Burials. 

